STM32DUINO is not an Arduino killer. It is simply a re-worked and improved core derived from the LeafLab original core code for the STM32F103 Maple branded boards.

Arduino.cc is constantly evolving hardware and the IDE is actively being enhanced. Refer to: https://store.arduino.cc/usa/
which shows new hardware.

STM32DUINO is simply a non-official split from the Arduino official line-up which started when the STM32F103 discussion thread became far too long to be used by Arduino forum members who jumped on the bandwagon later. It was then, somewhat like now, difficult for newcomers to get started because the reference documentation was spread across hundred of posts. We early members had a belief that the STM32F1XX boards would be used by more advanced Arduino users who had needs for more resources at the silicon level: clock, SRAM, and Flash. Little was done early on to make the newbie road easy as we all told newbies to start with "UNO" or any of the official boards because the Arduino forum is moderated and great volumes of reference materials existed online and in commercial publications.

The "Arduino IDE" is part of our heritage and the core software is organized for that mindset. We have members that use other IDE's and swear by them and that is OK. But the core and rewritten libraries are structured to be used with the Arduino IDE; no one is going to penalize you for stepping out of bounds, but you do so at the risk of braving your adventure alone. I do believe that this forum now has enough diversity to support almost any IDE choice, however there are no guarantees.

I really agree about the idea that stm32 port is the ideal "Arduino killer".

For some arduino users some of the times, maybe. For others, no.

I'm not an arduino user. But for most of my projects, I ran the cpu at frequencies as low as possible, sometimes into the 100Khz range, because I don't need the performance and headaches associated with high speed operations.

So I'm sure there are many such users out there a plain old AVR satisfies 99% of their needs 99% of the time. For that 1% of the time, maybe they will use the stm32 port, or go native.

All these are part of arduino hype....
Too many boards, most of them just a marketing trick of some companies to include the "arduino" mark on their products. Except AVR based arduino and less for zero/due, all others are overpriced, mostly unsupported and not commonly used.